ABSTRACT The Mentored Research Scientist Development Award (K01) will support my long-term career objective of becoming an independent investigator who specializes in improving health behaviors and preventing chronic disease development in high-risk groups, including aging populations and those receiving nutrition assistance. Older adults have a higher risk of chronic disease, including several conditions strongly associated with poor nutrition. Increased intake of fruits and vegetables has been shown to lower the risk of multiple chronic diseases. However, very few older adults consume the recommended amounts of fruits and vegetables, especially those with limited income. While most adults in the U.S. still visit a store to buy groceries at least once a week, online grocery shopping is rapidly expanding in popularity, including among older adults. The growth in online grocery shopping offers a promising opportunity to tailor healthy eating interventions to online food retail environments. However, to our knowledge, no research has evaluated interventions designed to promote healthier online food purchases among low-income older adults. To address these gaps in the literature, the specific aims of this proposal are to 1) develop the components of a behavioral economics strategy (i.e., healthy bundle defaults) to influence diet behaviors; 2) characterize the online grocery shopping behaviors and attitudes of low-income older adults nationally; and 3) examine the extent to which ?healthy bundles defaults? and other behavioral economic strategies increase fruit and vegetable purchases among low- income adults in an online randomized controlled experiment. Data to inform the development of ?healthy bundle defaults? in Aim 1 will come from the National Household Food Acquisition and Purchase Survey (FoodAPS), a nationally representative survey of household food purchases and acquisitions, including Supplemental Nutrition Assistance Program (SNAP) households. For Aims 2 and 3, I will recruit a nationwide nonprobability panel of 2,528 low-income adults aged >50 years through Survey Sampling International (SSI), an online surveying company that recruits volunteer research participants through their online panels and other online communities. The findings from the proposed research will support the development of novel and much- needed approaches to improving food purchases in an aging population with an elevated risk of developing nutrition-based diseases. My training goals closely parallel my research aims and will further enhance my understanding of: 1) aging and health, 2) behavioral economics, 3) experimental research methods, and 4) survey design and development. This training will be augmented with additional professional development activities, including attending and presenting at national academic meetings to disseminate findings. The project builds upon the exceptional resources and mentoring at NYU School of Medicine and other institutions to train me in key new areas, bolster applications for competitive funding, provide opportunities for collaboration, and attain research independence.